Should he run, Rivera could face 89-year-old Sen. Frank Lautenberg, who has yet to say whether he is running for re-election in 2014, and Newark Mayor Cory Booker, 43, a Democrat who has announced for the seat.

Rivera said he has "been in touch with some people in the Republican Party in New Jersey," The (Newark, N.J.) Star-Ledger reported.

"Fasten your seat belt," he said.

Clinton leaves post; Kerry takes over

WASHINGTON, Feb. 1 (UPI) -- Secretary of State Hillary Clinton ended her tenure Friday as former Sen. John Kerry of Massachusetts was sworn in as the top U.S. diplomat.

Clinton addressed State Department employees in the afternoon before leaving her post.

"As I look back over these past four years, I am very proud of the work we have done together. Of course, we live in very complex and even dangerous times, as we saw again just today at our embassy in Ankara, where we were attacked and lost one of our foreign service nationals and others injured," Clinton said. "But I spoke with the ambassador, and the team there, I spoke with my Turkish counterpart and I told them how much we valued their commitment and their sacrifice.

Clinton said she sees hope for the future.

"I know that the world we are trying to help bring into being in the 21st century will have many difficult days, but I am more optimistic today than I was when I stood here four years ago, because I have seen day after day the many contributions that our diplomats and development experts are making to help ensure that this century provides the kind of peace, progress and prosperity that not just the United States, but the entire world, especially young people, so richly deserve."

Kerry, who resigned his Senate seat after his confirmation earlier this week, was sworn in Friday during a private ceremony. Kerry officially begins his duties Monday.

Australian pranksters won't face charges

LONDON, Feb. 1 (UPI) -- The Australian radio personalities whose prank call to the hospital room of the Duchess of Cambridge led to the suicide of a nurse will not be charged.

Prosecutors had considered charging the radio personalities with manslaughter in the death of Jacintha Saldanha, but concluded that there was not enough evidence, The Daily Telegraph reported.

Saldanha was the nurse at the King Edward VII hospital in London who forwarded a call to the room where a pregnant Kate Middleton was after the DJs tricked her into believing the call was from Queen Elizabeth.

The nurse killed herself three days later.

Malcolm McHaffie, the deputy head of special crime for the Crown Prosecution Service, said Friday his office has weighed charging the two with violations of communications and data protection laws but decided prosecution would not be in the public interest.

The two, Mel Greig and Michael Christian, made tearful apologies for the prank, but have been off the air since the death of Saldanha.

BOSTON, Feb. 1 (UPI) -- Former U.S. Sen. Scott Brown, R-Mass., said Friday he will not run to succeed former Sen. John Kerry, who left the Senate to become secretary of state.

Brown won a special election in 2010 to succeed the late Sen. Ted Kennedy, but lost his re-election bid in November when Democratic nominee Elizabeth Warren was elected.

He issued a statement saying he has "received a lot of encouragement" to run "and my competitive instincts were leading in the same direction."

"I was not at all certain that a third Senate campaign in less than four years, and the prospect of returning to a Congress even more partisan than the one I left, was really the best way for me to continue in public service at this time," he said.

Brown's announcement came one day after Charlie Baker -- a former state secretary of Administration and Finance and the GOP nominee for governor in 2010 -- said he will not run in the Senate special election. Baker urged Republican former Gov. William Weld to run if Brown decided not to, the Boston Herald reported.

Former Lt. Gov. Kerry Healey is another possible candidate, The Boston Globe said.

So far, the only declared candidates for the special election are U.S. Rep. Stephen Lynch and U.S. Rep. Edward Markey, both Democrats.

WASHINGTON, Feb. 1 (UPI) -- Steven Chu, the Nobel laureate who became U.S. energy secretary, announced Friday he is leaving the post to return to the academic world.

Chu sent a letter to department employees saying he wants to resume teaching and research, USA Today reported. He said he will go as soon as his successor has been confirmed by the Senate.

"As a Nobel Prize-winning scientist, Steve brought to the Energy Department a unique understanding of both the urgent challenge presented by climate change and the tremendous opportunity that clean energy represents for our economy," President Obama said in a statement. "And during his time as secretary, Steve helped my administration move America towards real energy independence."

Chu graduated from the University of Rochester and received a doctorate in physics from the University of California at Berkeley. The work that won him a Nobel Prize in physics was done at Bell Labs where he studied using lasers to trap and cool atoms.

In 1987, he joined the faculty of Stanford University and in 2004 moved to Berkeley, where he headed the Lawrence Berkeley National Laboratory and taught physics.

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